Face type seals, that is, seals having at least one axial sealing face for forming a sealed condition in engagement with an opposing flat surface, are well known in the art. Commonly, O-rings are used as face seals. Other known face seals include bifurcated elastomeric sealing elements having a peripheral rim for isolating or shielding a main sealing element from sudden pressure changes on the rim side of the seal which can cause extrusion of the main sealing element. This rim also protects the main sealing element during handling and installation. To provide a satisfactory sealing function under high pressure conditions, particularly to avoid extrusion of the elastomeric sealing components into adjacent spaces, the known face seals also typically have a relatively large area of contact with the opposing surface, which is known as the seal area. However, a large seal area has the accompanying shortcoming of a correspondingly large joint or seal separation load, that is, a force generated by the seal urging to open or separate the sealed joint. The larger the joint separation load, the greater the force required to keep the joint closed. This means that more and/or larger fasteners are required, which increases cost.
The opposing surface with which the face seal forms the sealed condition is typically lapped, ground or milled to achieve a high degree of flatness. However, the lapping, grinding and milling operations can produce very small scratches that extend across the surface, thereby providing a potential leak path past the seal. Scratches can also be accidentally formed across the surface during handling. To avoid these problems, manufacturers typically impose stringent surface finish requirements on these surfaces which add to their manufacturing cost.
Additionally, many manufactured assemblies include component parts requiring more than one face seal therebetween, for instance, for forming sealed conditions around multiple passages or conduits extending between the components, requiring that the multiple sealed conditions be formed simultaneously as the components are assembled. This can be problematic in instances wherein the opposed surfaces with which the seals are to form the sealed conditions are not uniformly spaced apart, as this can result in varying degrees of compression of the respective seals when the components are assembled. To overcome the above-referenced scratching problem, it is known to produce the opposing surfaces with which the seals are to form the sealed conditions using spot facing and counterboring techniques wherein only circumferentially extending scratches are produced. This enables flatness and surface finish tolerances to be relaxed. It has also been found that many known spot face machines can hold very close axial or depth tolerances such that multiple spot faces produced on a component can be very closely co-planar. This is significant because when two components are assembled, a very uniform spaced apart relationship between the spot faces and opposing surfaces can be achieved. When the components are fastened together with multiple face seals installed for forming sealed conditions with the respective spot faces, more uniform, predictable sealing characteristics can be achieved.
What is now desired, therefore, is a face seal to more fully exploit the advantages of the available counterboring and spot facing techniques, which seal lowers manufacturing and assembly costs, and provides more uniform, positive sealing capabilities.
Accordingly, the present invention is directed to overcoming one or more of the problems as set forth above.